Rear end ratios-Comments please
Thread Starter
Race Director
Joined: Dec 2004
Posts: 10,332
Likes: 63
From: PARADISE
St. Jude Donor '09-'11-'12-'13-'14
Rear end ratios-Comments please
The kid is thinking about a lower rear end ratio for his 6 speed '01. Anyone had any experience with 4.10, 4.56, and 4.88 ratios or something close? He wants an off the line rocket with reasonable rpm in top gear. He's done the calc's and even the 88's don't look too bad.
Any comments welcome...Dad.
Any comments welcome...Dad.
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
Originally Posted by claysmoker
The kid is thinking about a lower rear end ratio for his 6 speed '01. Anyone had any experience with 4.10, 4.56, and 4.88 ratios or something close? He wants an off the line rocket with reasonable rpm in top gear. He's done the calc's and even the 88's don't look too bad.
Any comments welcome...Dad.
Any comments welcome...Dad.
3.90's (what I went with) and 4.10's
Nothing lower available.
Many folks have been happy with either choice.. Good luck.
Drifting
Joined: Dec 2004
Posts: 1,295
Likes: 236
From: Oshawa Ontario
I put 4.10's into my LS1 Z28 with an A4, so I'm sure they would be the right gear to use with a 6-speed, considering 6th gear is like "double over-drive"
.
I know that lower ratios (at least to 4.56) are available for standard GM 10-bolt and 12-bolt rear ends, but I never knew that 4.10 was the lowest for a C5??
...guess ya learn something new everyday?
.I know that lower ratios (at least to 4.56) are available for standard GM 10-bolt and 12-bolt rear ends, but I never knew that 4.10 was the lowest for a C5??
...guess ya learn something new everyday?
Safety Car
Joined: Jul 2001
Posts: 4,661
Likes: 67
From: Ocean Springs MS
Originally Posted by Cap'n Pete
I know that lower ratios (at least to 4.56) are available for standard GM 10-bolt and 12-bolt rear ends, but I never knew that 4.10 was the lowest for a C5?? ...guess ya learn something new everyday?
...guess ya learn something new everyday?
Racer
Joined: Mar 2003
Posts: 292
Likes: 0
From: Southbury CT
Originally Posted by 2002Z06Yellow
4.10s already put a lot of stress on the car. anything lower and the car will face reliability issues IMO
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Burning Brakes
Joined: Aug 2003
Posts: 1,229
Likes: 1
From: Palm Bay FL
I have 4.10s in my 6-spd Vert. They make a major difference in the car's acceleration and handling. My Vert is lightly-modified (340 rear-wheel HP), and I can break the stock tires loose by mashing the gas on a roll in 1st. I think if I were doing it again, I'd go with the 3.90s.
Alll in all, a worthwhile mod.
Alll in all, a worthwhile mod.
Pro
Joined: Nov 2003
Posts: 667
Likes: 0
From: san antonio tx
Originally Posted by Tree
Could you elaborate? Besides increasing the engine speed for a given MPH, what other stresses should I be considering?
Lepus-temperamentalus
Joined: Apr 2004
Posts: 5,827
Likes: 5
From: Roswell Ga
It's not so much the 4:10's as what you'd do after you had the 4:10's.
Obviously, with that sort of a gear, you'd go racing where you'd quiickly find out that you didn't have any traction, so you'd put slicks or drag radial on the car to get the traction back, right?
So what you'd do is effectively increase the amount of torque going to the rear wheels during your start. That increase in torque wouldn't be able to relieve the stress by spinning the tires, so the stress would go to the next weakest part of your drivetrain, my guess would be the universal joints, but that's just a guess.
There's always going to be some part that's the weakest link and whenever you increase the stress, that's where it's going to go. Generally it's the tires but if you do something to increase traction, it's going to be something else. That's why race cars use things like driveshaft safety loops, transmission scatter shields and such. Somethings gotta give!
Obviously, with that sort of a gear, you'd go racing where you'd quiickly find out that you didn't have any traction, so you'd put slicks or drag radial on the car to get the traction back, right?
So what you'd do is effectively increase the amount of torque going to the rear wheels during your start. That increase in torque wouldn't be able to relieve the stress by spinning the tires, so the stress would go to the next weakest part of your drivetrain, my guess would be the universal joints, but that's just a guess.
There's always going to be some part that's the weakest link and whenever you increase the stress, that's where it's going to go. Generally it's the tires but if you do something to increase traction, it's going to be something else. That's why race cars use things like driveshaft safety loops, transmission scatter shields and such. Somethings gotta give!
Last edited by JACKAL0PE; Jan 18, 2005 at 03:48 PM.
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
Originally Posted by 2002Z06Yellow
4.10s already put a lot of stress on the car. anything lower and the car will face reliability issues IMO
Just look through all the posts where the damn diff separated from the back of the transmission!
Those lower ratios reduce the diff assembly's torque-handling capabilities.
Frankly, I'd be surprised that DTE would peruse even lower ratios, given the failures they've already seen.. Maybe they are "playing the odds".
3.90's are more than enough for me.
Burning Brakes
Joined: Oct 2002
Posts: 797
Likes: 1
From: Sunny Earthquake Country, USA On the Left Coast (which is becoming more Right!)
I'm a product of the '50's...
Originally Posted by claysmoker
Thanks for the info. The 56's and 88's go back to my 55 Chevy in 1966,(oh, how I wish I still had that car).
In 1962, I had a 1956 Austin Healy with a '62 fuely short block, boggin' quads and I spliced in a Chev 4.56 punkin into the full floating Healy axle and somehow that seemed appropriate at the time!
Now I couldn't imagine a 4.56/4.88 in my C5. I have a big engine and my 3.90 seems just perfect!
Roy
Last edited by 7.0sc SuperVette; Jan 19, 2005 at 04:20 AM.
Burning Brakes
Joined: Oct 2002
Posts: 797
Likes: 1
From: Sunny Earthquake Country, USA On the Left Coast (which is becoming more Right!)
Pressure on teeth...
Originally Posted by 2002Z06Yellow
I dont pretend to be an expert so someone might help me out here. But i think there are less teeth on this gear. thus the pressure will be divided will be higher on each one.
Roy
Last edited by 7.0sc SuperVette; Jan 19, 2005 at 07:56 PM.
Heel & Toe
Joined: Dec 2004
Posts: 21
Likes: 0
Originally Posted by 2002Z06Yellow
I dont pretend to be an expert so someone might help me out here. But i think there are less teeth on this gear. thus the pressure will be divided will be higher on each one.
Drifting
Joined: Nov 2003
Posts: 1,288
Likes: 2
From: tucson az
my 4.10 a4 is a daily driver that i autocross twice a month....i kept the stock converter to keep the driveabilty as close to stock as possible...it works great!...normal in town driving is sweet as can be, raving on it is way FUN!!!!!!!! 